Impac o acidi ica ion and p o ein o i ica ion on heological
and he mal p ope ies o whea , co n, po a o and apioca
s a ch-based glu en- ee b ead doughs
Ma ina Villanue a1, Sand a Pé ez-Qui ce1, Concha Colla 2, Felicidad Ronda1
1 Depa men o Ag icul u e and Fo es y Enginee ing, Food Technology, College o Ag icul u al and Fo es y
Enginee ing, Uni e si y o Valladolid, A . Mad id, 44, 34004 Palencia, Spain.
2 Ce eals and Ce eal-based P oduc s, Food Science Depa men , Ins i u o de Ag oquímica y Tecnología de
Alimen os, IATA-CSIC, A da. Ca ed á ico Agus ín Esca dino 7, 46980 Pa e na, Spain.
Abs ac
The s udy o new glu en- ee (GF) oods is necessa y since consume s in ole an o glu en a e mo e
and mo e equen ly diagnosed. The s udy e alua ed he impac o acidi ica ion -wi h ace ic+lac ic
blend a 0.5 g/100 g le el- and p o ein o i ica ion -wi h caseina e (CA) o soy-p o ein isola e (SPI)-
on he heological ea u es o whea , co n, po a o and apioca s a ch-based b ead doughs. Oscilla o y
and c eep- eco e y es s we e ca ied ou o cha ac e ise hei iscoelas ic beha iou , and
he momechanical es s we e pe o med o assess hei isco-me ic pe o mance. Dough s ickiness
was also measu ed. The acid blend had a modula o e ec on dough heological p ope ies ha
depended on bo h he ype o p o ein and he sou ce o he s a ch. P o eins s uc u ed and
s eng hened he doughs especially hose made wi h SPI-po a o s a ch and CA-whea s a ch
mix u es. Acidi ica ion dec eased G’ and G’’ moduli un il 70% wi h espec o unacidi ied doughs. The
e ec was much mo e ma ked in p o ein- o i ied doughs. A signi ican inc ease in all pas ing
iscosi ies was obse ed wi h p o ein addi ion, pa icula ly in he case o CA. In gene al, p o ein
addi ion dec eased dough s ickiness whe eas he opposi e e ec was no ed wi h he p esence o acid.
Acidi ica ion o p o ein-en iched s a ch ma ices modula e dough heological p ope ies which a e
o ele ance in GF p oduc s de elopmen .
Keywo ds: Ace ic acid; Glu en-F ee Doughs; Lac ic acid; P o eins; Rheology
1. In oduc ion
The de elopmen o p oduc s o consume s wi h glu en- ela ed diso de s cons i u es a p io i ized
and challenging opic in s a ch-based goods a ea. In addi ion o diagnosed pa ien s, also people
looking o non alle genic ing edien s con ibu e o a g owing GF ma ke ca ego y; he e o e he
isen a ie y o o e ed i ems seems o be an impe ious need.
Unde s anding he heological cha ac e is ics o ood ma e ials is o key impo ance in designing new
p oduc s. In b eadmaking applica ions, he heological p ope ies o doughs a ec bo h dough
handling abili y and b eadmaking p ocess (Hoseney & Smewing, 1999), and hence inal b ead
cha ac e is ics (Ronda, Pé ez-Qui ce, & Villanue a, 2017). Fundamen al and empi ical heological
p ope ies o doughs also in o m abou in e ac ions among ing edien s and he c ea ion o s uc u e
a mac omolecula and mac oscopic le els, espec i ely (Ronda, Villanue a, & Colla , 2014).
Glu en p o ein ma ix is a key ac o in b eadmaking. Besides con ibu ing o he wa e abso p ion
capaci y o he dough, glu en p o ides ex ensibili y, elas ici y and cohesi eness o b ead dough
allowing he e men a ion gas o be occluded and main ained in he liquid phase du ing he dough
de elopmen , leading o well-de eloped high-g ade b eads (Wiese , 2007). The elimina ion o glu en
in baked p oduc s esul s in dele e ious e ec s in e ms o quali y a ibu es o p oduc s, nu i ional
cha ac e is ics, and consume accep ance (Naqash, Gani, Gani, & Masoodi, 2017). The mos
commonly used s a ches in GF b ead-making a e maize s a ch and po a o s a ch bu also s a ches
om apioca, whea and ice among o he (Masu e, Fie ens, & Delcou , 2016). Howe e , hese
s a ches ha e minimal s uc u e-building po en ial and, hus, a e equen ly used along wi h p o eins
and hyd ocolloids (Cap iles & A êas, 2014). P o eins and polysaccha ides a e p esen oge he in
many kinds o ood sys ems, and bo h ypes o ood mac omolecules con ibu e o he s uc u e,
ex u e and s abili y o ood h ough hei hickening o gelling beha iou and su ace p ope ies
(Doublie , Ga nie , Rena d, & Sanchez, 2000). The inco po a ion o p o eins in GF ma ices is ocused
on he nu i ional enhancemen and on he imp o emen o b ead inal cha ac e is ics (physical and
ex u al).
In e - and in a-molecula in e ac ions es ablished be ween exogenous p o eins and s a ch
molecules, main esponsible o dough s uc u ing, ce ainly depend on dough pH (Houben,
Höchs ö e , & Becke , 2012; Ronda e al., 2014). Acidi ica ion h ough lac ic and ace ic acid addi ion
con e s sui able p ope ies o inal b eads ei he when p oduced by he exogenous mic o lo a o
added o b eadmaking ma ices Acidi ica ion imp o ed he odou and as e o esh b ead and
inc eased he p o ease and amylase ac i i ies ha led o e a ded s aling du ing s o age (Moo e, Dal
Bello, & A end , 2008). Acidi ica ion by ace ic acid and lac ic acid addi ion ha e shown o p o ide a
signi ican impac in p o ein-en iched ice s a ch-based doughs p ope ies (Ronda e al., 2014) and
in he quali y and shel -li e o ice s a ch-based b eads o i ied wi h CA, SPI and pea p o ein isola e
(Villanue a, Mau o, Colla , & Ronda, 2015). Taken in o accoun he impo ance o o he s a ches, as
po a o, apioca, co n and whea , on he de elopmen o GF p oduc s, he s udy o he e ec o
acidi ica ion on p o ein-en iched doughs made wi h heses s a ches seems imely.
In GF p oduc s, s a ch becomes he p ima y s uc u al elemen due o he lack o glu en, mainly
du ing he baking s age, when he ba e empe a u e eaches s a ch gela iniza ion alues. Howe e ,
s a ches om di e en sou ces di e ma kedly on wa e binding capaci y which a ec s d ama ically
dough consis ency and dough de elopmen du ing e men a ion, and he quali y o he inal p oduc s
(Ronda e al., 2017). Wi h his in mind, he aim o he p esen s udy was o e alua e he impac o he
addi ion o 0.5 g/100 g (s a ch+p o ein) o ace ic + lac ic acid mix u e o di e en GF b ead doughs
made wi h maize, po a o, apioca o whea s a ches o i ied wi h CA o SPI (a 5 g/100 g
(s a ch+p o ein) le el) on he iscoelas ici y, s ickiness and pas ing p ope ies o b ead doughs.
2. Ma e ial and me hods
2.1. Ma e ials
Co n, po a o and whea s a ches we e supplied om Fe e Alimen ación S.A. (Ba celona, Spain), and
apioca s a ch om Ca gill S.L. (B enn ag, Se illa, Spain). Sal , suga (Azuca e a, To o, Spain) and
sun lowe oil Coosu P emium (Jaen, Spain) we e pu chased om he local ma ke . Hyd oxy-p opyl-
me hyl-cellulose (HPMC, Me hocel-K4M-Food-G ade) was p o ided as a gi by Dow Chemical
(Midland, USA). P o eins used in GF o mula ions we e: soybean p o ein isola e (SPI) Sup o 500-E IP
gi en by P o eedo a hispano-holandesa S.A. (Ba celona, Spain) and calcium caseina e (CA) by A mo
p o eines (Sain -B ice-en-Coglès, F ance). Ace ic acid and lac ic acid o analy ical g ade om Pan eac
(Ba celona, Spain) we e used. Dis illed wa e was used o p epa e all he suspensions o s udy he
pas ing p o iles and ap wa e was used o make GF doughs.
2.2. Me hods
Dough p epa a ion
A s aigh dough p ocess was pe o med in duplica e pe o mula ion, using he ollowing o mula
on a 100 g s a ch (o s a ch+p o ein) basis: 6 g oil, 5 g suc ose, 1.5 g sal , 2.0 g HPMC and 75 g wa e .
CA and SPI we e added a 0 o 5 g/100 g (s a ch + p o ein basis) le els and doughs we e
supplemen ed wi h (0.1 + 0.4) g/100 g (s a ch + p o ein basis) o ace ic+lac ic acid when acid-
ea men was applied. The expe imen al design esul ed in 24 di e en combina ions (Table 1). GF
dough-making was achie ed by blending i s solid ing edien s and oil in a ki chen-aid p o essional
mixe KPM5 (Michigan, USA) a speed 2. Then wa e was added and hand mixed. Finally he dough
was mixed wi h dough hook a a speed 4 o 8 min. Acid blend, when added, was dilu ed in a small
pa o wa e and adjus ed o he dough be o e he mixe was powe ed on.
Table 1. Randomized expe imen al design
Fo mula
S a ch
P o ein
Ace ic/Lac ic Acid*
1
Po a o
SPI
0.1/0.4
2
Whea
0
0.1/0.4
3
Po a o
SPI
0
4
Co n
SPI
0
5
Co n
SPI
0.1/0.4
6
Co n
CA
0
7
Tapioca
SPI
0
8
Whea
0
0
9
Tapioca
SPI
0.1/0.4
10
Co n
0
0.1/0.4
11
Co n
CA
0.1/0.4
12
Po a o
0
0
13
Tapioca
CA
0
14
Tapioca
0
0.1/0.4
15
Po a o
CA
0.1/0.4
16
Whea
SPI
0.1/0.4
17
Whea
CA
0
18
Tapioca
CA
0.1/0.4
19
Tapioca
0
0
20
Po a o
CA
0
21
Co n
0
0
22
Whea
CA
0.1/0.4
23
Whea
SPI
0
24
Po a o
0
0.1/0.4
P o ein: 0: wi hou p o ein, CA: Wi h 5g/100g Calcium caseina e, SPI: Wi h 5g/100g soybean p o ein isola e. *g/100g
wi h espec o s a ch o s a ch+p o ein basis
2.3. Dough measu emen s
pH and o al i a able acidi y o doughs
To al i a able acidi y (TTA) was measu ed on en g ams o dough blended wi h 100 mL o a solu ion
o ace one in wa e (5 mL/100 mL) unde cons an s i ing. The i a ion was ca ied ou agains 0.1
mol/L NaOH un il a inal pH o 8.5. The esul s we e exp essed as milliequi alen s o lac ic acid/g o
dough. This measu emen was aken in iplica e on unyeas ed doughs.
Fundamen al heological es s
Oscilla o y and c eep– eco e y es s we e ca ied ou wi h RheoS ess-1 heome e (The mo Haake,
Ka ls uhe, Ge many) wi h pa allel pla e geome y (60 mm diame e ) o se a ed su ace and wi h 3-
mm gap. The excess o dough was emo ed, and aseline oil was applied o co e he exposed sample
su aces. All measu emen s we e done a 25 °C. Be o e each assay he dough was allowed 10 min o
elaxa ion. F equency sweeps we e ca ied ou om 10 o 1 Hz in he linea iscoelas ic egion (LVR).
A cons an s ess alue o 1 Pa was chosen o he equency sweeps o all doughs. S ess sweeps
we e ca ied ou om 0.1 o 100 Pa a 1 Hz. F om he cu es, he maximum s ess beyond which he
dough s uc u e was b oken, τmax, was es ablished. F equency sweep da a we e i ed o he powe
law model as in p e ious wo ks (Ronda e al., 2014). Wi hin he applied equency ange, he
mechanical spec a i ed he powe law model wi h R2 alues abo e 0.99.
C eep es s we e pe o med by imposing a s ep o shea s ess in he LVR and ou side he linea
iscoelas ic egion (OLVR). Fo he c eep s udy in he LVR, a cons an shea s ess o 1 Pa was applied
o 150 s, while in he eco e y phase he s ess was suddenly emo ed and he sample was allowed
o 300 s o eco e he elas ic (ins an aneous and e a ded) pa o he de o ma ion. Fo he OLVR
s udy, a cons an shea s ess o 50 Pa was applied o 60 s and he sample was allowed o eco e
o 180 s a e emo ing he load. Each es was pe o med in iplica e. The da a om c eep es s
we e modelled o he 4-pa ame e Bu ge s model (Ronda e al., 2014).
Dough s ickiness
S ickiness was measu ed by ollowing he p ocedu e p oposed by G ausg ube , Ha zenbichle , &
Ruckenbaue (2003). A ex u ome e TA-XT2 om S able Mic osys em (Godalming, UK) p o ided
wi h a SMS/Chen-Hoseney de ice whe e he sample was placed, and a me hac yla e 25 mm cylinde
(P/25P) as comp ession cell, we e used. The posi i e maximum o ce (adhesi e o ce), was used o
measu e s ickiness. Six eplica es we e made o each dough.
Pas ing p ope ies
Viscome ic p o iles o o mula ed doughs om di e en s a ch sou ces and p o eins in acidi ied/no
acidi ied medium we e ob ained by using a Rapid-Visco-Analyse (RVA-4, Newpo Scien i ic,
Wa iewood, Aus alia) and p o ile S anda d 1. F eeze-d ied dough samples (Colla , 2003) we e
ans e ed (3.0 g o co n and whea s a ches, 2.5 g o apioca s a ch and 2.0 g o po a o s a ch o
14 g/100 g mois u e basis) in o canis e s and 25 ± 0.1 mL o dis illed wa e we e added and
p ocessed ollowing s anda d me hod. The pas ing empe a u e (PT), peak ime (P- ime), peak
iscosi y (PV), ough iscosi y (TV), b eakdown (BD), inal iscosi y (FV) and se back iscosi y (SB)
we e calcula ed om he pas ing cu e using The mocline . 2.2 so wa e. All measu emen s we e
pe o med in duplica e.
2.4. S a is ical analysis
S a g aphics Cen u ion .6 (Bi s eam, Camb idge, MN, USA) was used o non-linea eg essions and
mul i- ac o analysis o a iance. LSD (Leas Signi ican Di e ence) es was used o e alua e
signi ican di e ences (p < 0.05) be ween samples.
3. Resul s and discussion
3.1. pH and o al i a able acidi y o doughs
The pH o unacidi ied and p o ein- ee ma ices a ied depending on he s a ch sou ce, and ollowed
he o de : Tapioca (pH=5.9) < Co n (pH=6.1) < Po a o (pH=6.5) < Whea (pH=6.8) (Fig. 1a). P o ein
p esence sys ema ically inc eased he dough pH alue while he ace ic-lac ic blend p o ided a
dec ease ~ 2.5 uni s. The ype o p o ein and he s a ch sou ce also a ec ed he pH o he dough
h ough he signi ican (p<0.05) (p o ein x s a ch x pH) 3 d o de in e ac i e e ec (Fig.1a). Dough
pH inc eased wi h p o ein p esence be ween 3 % ( o whea and po a o s a ch doughs) and 18% ( o
apioca s a ch dough) depending on he s a ch sou ce. Acidi ica ion o con ol ma ices educed
signi ican ly (p<0.05) he pH om 6–6.7 o 3.4–3.6. Howe e , acidi ica ion o p o ein-en iched
doughs only dec eased pH o 4.3–4.8. The bu e ing e ec o p o eins, esponsible o he lowe e ec
o acidi ica ion on dough pH, was p e iously epo ed by Villanue a e al. (2015) o ice s a ch-based
doughs. Fig.1a shows he bu e ing e ec was signi ican ly highe o CA han SPI ega dless he
s a ch sou ce used o dough o mula ion; consequen ly, he pH o acidi ied CA-en iched doughs was
highe han hose o SPI-en iched doughs.
The TTA o con ol doughs (unacidi ied and p o ein- ee doughs) a ied signi ican ly (p<0.05)
depending on he s a ch sou ces (Fig.1a): Whea (0.0028 meq/g) < Tapioca (0.0039 meq/g) < Co n
(0.0077 meq/g) < Po a o (0.0100 meq/g). Acid addi ion inc eased he TTA o doughs om 0.008
meq/g o 0.034 meq/g on a e age. P o ein addi ion inc eased dough TTA bu he inc ease depended
on s a ch sou ce and p o ein ype as deno ed by he signi ican (p<0.05) 3 d o de in e ac ion
depic ed in Fig.1a. The inc ease was always highe o CA han SPI, in cohe ence wi h he highe
bu e ing e ec o he o me , also esponsible o he lowe dec ease o pH in acidi ied doughs in CA
p esence.

Figu e 1. pH and TTA alues (a) and maximum s ess alues, τmax (b) eco ded o samples wi h di e en s a ch sou ce, ype o p o ein
and acid addi ion. WP: doughs wi hou p o ein, CA: doughs wi h 5% calcium caseina e, SPI: doughs wi h 5% soy p o ein isola e. Void
ba s (p incipal axes) and discon inue lines (seconda y axes) co espond o doughs wi hou acid addi ion, illed ba s and con inuous
lines co espond o acidi ied doughs. E o ba s ep esen he mean s anda d de ia ion. Di e en le e s wi hin each g aph mean
s a is ically signi ican di e ences be ween means (p<0.05).
j
lnkmop
i
pqo s
b
gd
b
he
a
c
a
c
0
0,01
0,02
0,03
0,04
0,05
3
3,5
4
4,5
5
5,5
6
6,5
7
7,5
WP CA SPI WP CA SPI WP CA SPI WP CA SPI
Co n Po a o Tapioca Whea
TTA (meq/g)
pH
aab ab ab
e
b
a
c
ab ab
d
a
ab
ab ab ab ab b
ab aaab ab ab
0
4
8
12
16
20
24
28
32
WPCASPI WPCASPI WPCASPI WPCASPI
Co n Po a o Cassa a Whea
τmax (Pa)
a)
b)
3.2. Dynamic oscilla o y heology
The s ess sweep es s p o ided he τmax alue o maximum s ess doughs we e able o s and be o e
b eaking hei s uc u e (Fig.1b). The τmax alues o all doughs we e a ound 2–4 Pa (wi hou
signi ican di e ences among hem) wi h he excep ion o unacidi ied CA-en iched doughs made wi h
po a o, whea o apioca s a ches (maize s a ch doughs we e no a ec ed by CA addi ion). The τmax
o hese doughs we e much highe : 26, 19 and 12 Pa espec i ely. This could be due o he
o ganiza ion o casein micelles ha o m la ge sup amolecula en i ies u he conside ed as
sphe ical pa icles. They a e co e ed by κ-casein, which s abilizes hem in he suspension h ough
s e ic and elec os a ic epulsions. Mo eo e , he hai y su ace p e en s neu al polyme s om
adso bing on he micelles (Bou io , Ga nie , & Doublie , 1999) and Ca+2 ionic in e ac ions, which
pa ially can eplace he beha iou o disulphide b idges, could deli e simila heological
cha ac e is ics o glu en sys ems (S a hopoulos & O’Kennedy, 2008). The acid blend addi ion
coun e ac ed he CA s abiliza ion e ec and led o simila τmax alues han p o ein- ee ma ices.
Table 2 shows he single e ec s and Fig.2a he 3 d o de in e ac i e e ec s o ac o s s udied on
iscoelas ic pa ame e s ob ained om equency sweeps. Viscoelas ic beha iou o dough samples
co esponded o solid-like sys ems wi h s o age modulus alues (G’1) highe han loss modulus (G’’1),
sligh equency dependence (low a and b exponen s), and alues o ( an δ1) unde 1, in good
acco dance wi h ea lie esul s ound o acidi ied ice s a ch doughs en iched wi h p o eins ha
included SPI and CA p o eins (Ronda e al., 2014). The sligh dependence o he moduli on angula
equency (a and b alues anged 0.13–0.37) and he alues o phase shi angen ( an δ) a ying in
he ange 0.33–0.68 a e cha ac e is ics o he sys ems called pseudo-gels. This is in ag eemen wi h
ea lie obse a ions in GF doughs (Wi czak, Ko us, Ziob o, & Juszczak, 2010). S a ch sou ce a ec ed
signi ican ly (p<0.001) he iscoelas ic moduli. The highes G1’ and G1’’ moduli we e ob ained o
po a o s a ch doughs (17300 Pa and 9400 Pa on a e age, espec i ely) while he lowes alues we e
obse ed o whea s a ch (3000 Pa and 1700 Pa) (Table 2). Fac o s ela ed o he bo anical o igin o
s a ch esponsible o s a ch swelling such as amylose/amylopec in a io, molecula weigh o
amylose and amylopec in, hei dis ibu ion wi hin he g anule, g anule size, he lipid con en and
o he mino componen s (such as mine als and sal s) play a c ucial ole (Wa e schoo , Gomand,
Fie ens, & Delcou , 2015). The inco po a ion o p o eins also a ec ed ma kedly dough consis ency.
P o eins aised bo h iscoelas ic moduli, G1’ and G1’’, leading o a e aged inc eases o 145 and 130%
espec i ely wi h espec o he alues o non-p o ein added-doughs. O he au ho s also concluded
ha p o eins such as soy p o eins a ec ed ice dough consis ency since hey a e he main
componen s in ol ed in wa e abso p ion (Ma co & Rosell, 2008). The inc ease in ice based dough
consis ency was also p e iously epo ed as esul o SPI and CA addi ion (Ronda e al., 2014; Ma os
& Rosell, 2014).
Table 2. Single e ec s on pH. acidi y and he heological p ope ies om oscilla o y es s o glu en- ee b ead
doughs made wi h s a ches om di e en sou ces, wi hou o wi h p o ein (5 g calcium caseina e o soy
p o ein isola e pe 100 g o s a ch+p o ein) wi h o wi hou acid addi ion (ace ic+lac ic acid 0.1+0.4 g/100 g
s a ch+p o ein)
Va iable
Uni
Mean
Le el
S a ch
P o ein
Acid
pH o he medium
pH
5.43
1
5.38
b
4.90
a
6.65
b
2
5.48
c
5.74
c
4.21
a
3
5.32
a
5.63
b
4
5.52
d
SE
0.004
0.003
0.003
TTA
meq/g
0.0209
1
0.0218
b
0.0190
a
0.0079
a
2
0.0233
c
0.0225
c
0.0339
b
3
0.0190
a
0.0210
b
4
0.0193
a
SE
0.0002
0.0001
0.0001
Dynamic Oscilla o y Rheome y
G'1
Pa
7763
1
5803
c
3942
a
9990
b
2
17309
d
9205
b
5537
a
3
4959
b
10143
c
4
2982
a
SE
162
138
111
a
0.30
1
0.28
a
0.31
b
0.30
a
2
0.31
b
0.33
c
0.30
a
3
0.29
a
0.27
a
4
0.33
c
SE
0.01
0.004
0.003
G''1
Pa
4126
1
2741
b
2196
a
5332
b
2
9443
c
5411
c
2920
a
3
2590
b
4771
b
4
1731
a
SE
84
72
58
b
0.23
1
0.25
b
0.25
b
0.22
a
2
0.19
a
0.24
b
0.24
b
3
0.23
b
0.21
a
4
0.27
c
SE
0.01
0.01
0.005
an 
0.53
1
0.47
a
0.56
b
0.54
a
2
0.55
c
0.57
c
0.53
a
3
0.52
b
0.47
a
4
0.58
d
SE
0.01
0.005
0.01
c
-0.07
1
-0.03
c
-0.06
b
-0.08
a
2
-0.12
a
-0.09
a
-0.06
b
3
-0.07
b
-0.06
b
4
-0.06
b
SE
0.01
0.01
0.004
S a ch le el: 1: co n, 2: po a o, 3: apioca, 4: whea ; P o ein le el: 1: wi hou p o ein, 2: Calcium caseina e, 3: Soya p o ein
isola e; Acid le el: 1: wi hou acid addi ion, 2: wi h acid addi ion. Wi hin each pa ame e , di e en le e s in he
co esponding column mean s a is ically di e ences be ween means a p<0.05. TTA: o al i a able acidi y. G’1. G’’1. and
( an δ)1 ep esen he elas ic and iscous moduli and he loss angen a a equency o 1 Hz. The a, b and c exponen s
quan i y he dependence deg ee o dynamic moduli and he loss angen wi h he oscilla ion equency. SE: Pooled s anda d
e o
The esul s could be explained by he c ea ion o a obus c osslinked s uc u e in doughs by added
p o eins, especially in he case o SPI by glycinin and i s high wa e e en ion abili y (C ocke , Ie, &
Vodo o z, 2011). On he opposi e, dough acidi ica ion always dec eased bo h iscoelas ic moduli as
was also p e iously concluded o ice s a ch (Ronda e al., 2014). The ANOVA s udy showed ha all
he 2nd o de and 3 d o de e ec s signi ican ly (p<0.01) a ec ed G1’, G1’’ and an δ1. This means ha
he e ec o he p o ein ype depended on bo h he s a ch sou ce and he pH o he dough. As can be
seen in Fig.2a SPI p o ided he mos s eng hening e ec in po a o s a ch doughs, wi h inc eases up
o 250% in G1’ wi h espec o he p o ein- ee dough. Impo an inc eases in G’ and G’’ we e also
ound by Pa aşcu, Banu, Vasilean, & Ap odu (2016) when added SPI o po a o s a ch sys ems.
Howe e , in he case o whea s a ch was he CA-p o ein who had he highes e ec on dough
consis ency leading o inc eases in G1’ and G1’’ o 320% while SPI only led o an inc ease o 105%.
The e ec o bo h p o eins was simila in he case o co n and apioca s a ch doughs (Fig.2a). The
e ec o dough acidi ica ion on iscoelas ic moduli was always g ea e in he case o p o ein-en iched
doughs. The acidi ica ion o p o ein- ee doughs only p o ided a signi ican (p<0.05) e ec in he
case o po a o, wi h sligh dec eases in G1’ and G1’’o 14 and 18% espec i ely. Howe e , in p esence
o p o ein, he dec ease in he elas ic modulus, G1’, was 41 and 74% o SPI- and CA-en iched whea
doughs wi h espec o he non-acidi ied coun e pa s.
Simila endency was obse ed in co n and apioca doughs (Fig.2a). In bo h cases, an δ dec eased in
unacidi ied doughs as esul o p o ein addi ion, deno ing an inc ease in he p edominance o dough
elas ici y. In acidi ied doughs, bo h p o eins CA and SPI, led o di e en e ec s. Acidi ica ion o CA-
en iched doughs led o a ma ked inc ease in he loss angen , which indica es an inc emen in he
iscous o elas ic moduli a io, while in he case o SPI-added doughs a dec ease was obse ed. The
simila i ies be ween co n and apioca s a ches could be due o hei simila pa icle size and shape,
comple ely di e en om po a o ( e y big size) and whea (bi-modal size dis ibu ion wi h small and
big g anules) s a ches. These s uc u al di e ences and he e o e, hei unc ional p ope ies, could
change he beha iou o he con inuous phase o he dough which esul s in changes o iscoelas ici y.
Acco ding o Singh, Singh, Kau , Sodhi, & Gill (2003), he p esence o a high phospha e monoes e
con en and he absence o lipids and phospholipids in he po a o s a ch may also be esponsible o
he high G’ and G’’ o hei doughs. The p esence o phospholipids and he mo e igid g anules o co n
s a ch could explain he lowe consis ency o doughs.
3.3. C eep- eco e y es s
C eep- eco e y es s we e ca ied ou bo h a 1 Pa, wi hin he linea iscoelas ic egion (LVR), and
a 50 Pa, ou side he linea iscoelas ic egion (OLVR). The esul s wi hin he LVR a e easie o
co ela e wi h he molecula s uc u e o he sample componen s. Howe e , du ing he baking
p ocess (mixing, moulding, e men a ion, baking) he doughs a e subjec ed o s ess ou side he LVR.
The e o e, OLVR es s a e use ul o p edic ing he de o ma ions ha he doughs will expe ience
du ing p ocessing.
0
10
20
30
40
50
60
70
80
90
100
0
500
1000
1500
2000
2500
3000
3500
0 200 400 600 800
Tempe a u e (ºC)
Viscosi y (mPa·s)
Time (s)
0
10
20
30
40
50
60
70
80
90
100
0
500
1000
1500
2000
2500
3000
3500
0 200 400 600 800
Tempe a u e (ºC)
Viscosi y (mPa·s)
Time (s)
0
10
20
30
40
50
60
70
80
90
100
0
500
1000
1500
2000
2500
3000
3500
0 200 400 600 800
Tempe a u e (ºC)
Viscosi y (mPa·s)
Time (s)
0
10
20
30
40
50
60
70
80
90
100
0
500
1000
1500
2000
2500
3000
3500
0 200 400 600 800
Tempe a u e (ºC)
Viscosi y (mPa·s)
Time (s)
Figu e 3. E ec o acidi ica ion and p o ein o i ica ion on iscome ic p o iles o b ead doughs made om co n (a), whea (b), po a o (c) and apioca
(d) s a ches. Doughs wi hou p o ein a e ep esen ed by , wi h 5% calcium caseina e by , and wi h 5% soy p o ein isola e by
. Doughs wi h acid addi ion a e ep esen ed by , wi h 5% calcium caseina e acidi ied by , and wi h 5% soy p o ein isola e acidi ied by
. The lines ep esen he iscome ic p o iles o aqueous s a ch dispe sions wi h a d y ma e con en iden ical o ha o he dough
dispe sion. The empe a u e p o ile is ep esen ed by in he second axis.
0
20
40
60
80
100
0
2000
4000
6000
0 200 400 600 800
Tempe a u e, ºC
Viscosi y, cp
Time (s)
a)
b)
c)
d)

4. Conclusions
Acidi ica ion and p o ein supplemen a ion modi ied he heological and pas ing p ope ies
o GF b ead doughs. Those e ec s a ied acco ding o bo h he s a ch sou ce and ype o
p o ein used as aw ma e ials and he p esence/absence o acid. In gene al, po a o s a ch
doughs e ealed he mos signi ican esul s. The inco po a ion o p o ein s eng hened he
dough, being s uc u ing especially signi ican in he case o CA addi ion o po a o, apioca
and whea s a ch doughs, showing highe τmax alues. Howe e , he e ec o p o ein on
iscoelas ic moduli depended on he ype o p o ein and s a ch sou ce. The acidi ica ion
esul ed in a weakening o he dough ma ices s uc u e. C eep- eco e y es made in and
ou side he LVR e ealed ha he addi ion o p o ein dec eased no ably he alues o
maximum compliance compa ed o con ol doughs wi hou p o ein, showing highe alues
wi h he addi ion o CA han SPI. In gene al, acid inco po a ion inc eased he alues o
compliance o all s a ches (en iched o no wi h p o eins) in and ou side he LVR, which
indica es a g ea e capaci y o de o ma ion o he doughs o a gi en s ess. P o ein p esence
inc eased he pas ing p o iles, bu wi h di e ences be ween he wo p o eins s udied. The
esul s o he p esen s udy can con ibu e o gene a ing new knowledge and he e o e he
de elopmen and inc ease o he GF baked p oduc s quali y o b oaden he ood p oduc
choices o GF p oduc s consume s. Addi ional s udies a e s ill equi ed o ex ensi e
e alua ion o he e ec o acidi ica ion on hese ma ices and i s applicabili y on he
b eadmaking p ocess.
Acknowledgemen
The au ho s hank he inancial suppo o he Minis e io de Economía y Compe i i idad and
he Eu opean Regional De elopmen Fund (FEDER) (AGL2015-63849-C2-1-R and
AGL2015-63849-C2-2-R) and Conseje ia de Educa ion (Jun a de Cas illa y Leon) / FEDER
(P ojec VA072P17). Ma ina Villanue a hanks he Jun a de Cas illa y León o he doc o a e
g an . The au ho s hank o Ca men M. Co as o he help wi h heological measu emen s.
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